The US is losing 36 million urban trees a year

Urban trees
CC BY 2.0 USDA/Flickr

The USDA Forest Service reveals that cities and communities are losing 175,000 acres of tree cover annually, while pavement, roads, and buildings are increasing.

Trees that grace cities and other residential areas are truly a treasure. Not only do they provide habitat for non-human city creatures, but they offer all kinds of health benefits to us human animals as well. And aside from the boosts of wellness they so generously proffer, the annual benefits of U.S. urban forests in considering air pollution removal, carbon sequestration, and decreased building energy use and the subsequent altered power plant emissions are estimated at $18 billion.

So you'd think that city planners and local governments would be all gung-ho about trees, right? But alas, the trees appear to be losing. Research from scientists with the USDA Forest Service estimate that between 2009 and 2014, tree cover in the country's urban and community areas declined each year by 36 million trees, or around 175,000 acres of tree cover.

Meanwhile, pavement and other impervious cover (like roads and buildings) increased at a rate of about 167,000 acres a year during the same period. Cue the Joni Mitchell.

"Nationally, urban/community tree cover declined from 42.9 percent to 42.2 percent. Twenty-three states had a statistically significant decrease in tree cover, with a total of 45 states showing a net decline," notes a statement for the research. "Trees improve air and water quality, reduce summer energy costs by cooling homes, reduce noise, mitigate runoff and flooding, and enhance human health and well-being, making them important to human health and urban and community infrastructure."

States or districts that have lost the greatest net percentage in urban/community tree cover were Rhode Island, the District of Columbia, Georgia, Alabama and Nebraska. Meanwhile, states with the greatest annual net loss in tree cover acreage were Georgia with 18,830 acres lost year, Florida with 18,060 acres and Alabama with 12,890 acres.

Mississippi, Montana and New Mexico fared slightly better with (albeit non-significant) increases in urban/community tree cover. Of all the states, Maine has the highest percentage in urban/community areas with 68 percent tree cover. At the other end, North Dakota ranked as having the lowest amount of urban/community tree cover with a mere 10 percent. (Note that grassland states like North Dakota historically only have trees along rivers – as was pointed out to me by a biologist on Twitter – which could account for lower percentages among those states' urban areas as well.)

“Urban forests are an important resource,” says co-author Dave Nowak from the USDA Forest Service’s Northern Research Station. “Urban foresters, planners and decision-makers need to understand trends in urban forests so they can develop and maintain sufficient levels of tree cover – and the accompanying forest benefits – for current and future generations of citizens.”

A table showing tree cover and impervious cover change by state is available here. And you can download the whole study here.

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